Discovery of an Ultraviolet Counterpart to an Ultrafast X-Ray Outflow in the Quasar PG 1211+143

Gerard A. Kriss, Julia C. Lee, Ashkbiz Danehkar, Michael A. Nowak, Taotao Fang, Martin J. Hardcastle, Joseph Neilsen, Andrew Young

Research output: Contribution to journalArticle (Academic Journal)peer-review

11 Citations (Scopus)

Abstract

We observed the quasar PG 1211+143 using the Cosmic Origins Spectrograph on the Hubble Space Telescope in 2015 April as part of a joint campaign with the Chandra X-ray Observatory and the Jansky Very Large Array. Our ultraviolet spectra cover the wavelength range 912─2100 Å. We find a broad absorption feature (∼ 1080 {km} {{{s}}}-1) at an observed wavelength of 1240 Å. Interpreting this as H I Lyα, in the rest frame of PG 1211+143 (z = 0.0809), this corresponds to an outflow velocity of −16,980 {km} {{{s}}}-1 (outflow redshift {z}{out}∼ -0.0551), matching the moderate ionization X-ray absorption system detected in our Chandra observation and reported previously by Pounds et al. With a minimum H I column density of {log} {N}{{H}{{I}}}> 14.5, and no absorption in other UV resonance lines, this Lyα absorber is consistent with arising in the same ultrafast outflow as the X-ray absorbing gas. The Lyα feature is weak or absent in archival ultraviolet spectra of PG 1211+143, strongly suggesting that this absorption is transient, and intrinsic to PG 1211+143. Such a simultaneous detection in two independent wavebands for the first time gives strong confirmation of the reality of an ultrafast outflow in an active galactic nucleus.
Original languageEnglish
JournalAstrophysical Journal
DOIs
Publication statusPublished - Feb 2018

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